Fullscreen(scanout/vrr): both cursor and primary layer stutter and may lock up

[Vixea]

A follow up to what I understood should've or was likely to have been fixed(at least with more powerful dgpu display engines?) by #1020
Anyway the description of the problem from what I understand:
When in fullscreen or scanout the display engine in the GPU can be overwhelmed causing dropped, stutters, (whatever you wanna call it) frames. If it can't be reproduced on a desktop system I would recommend trying an all amd laptop(one igpu and dgpu) which is what I'm currently reproducing it with

[Drakulix]

Yeah, it would be great if I had all the hardware in the world to test on. /s

Jokes aside, so you are experience stuttering on an AMD system with an iGPU and dGPU for a fullscreen title?

Can you tell me some more:

• What framerate/resolution are you targetting?
• VRR?
• Are there additional displays?
• What gpu is the display connected to, which gpu is the game running on?
• Anything suspicious in cosmic-comp or kernel logs?
• Can you get a dump of drm_info, while your game is running (e.g. via ssh), so we can easily confirm that direct scanout is actually in use?

Thanks for the bug report. :)

[Vixea]

1920*1200 at 165 Hz
Auto
No
Maybe I'm seeing a whole lot of repeating(what looks like the) amdgpu driver initing - https://pastebin.com/cEzWkEm9

https://pastebin.com/ZvfZGd0R

[Vixea]

https://pastebin.com/fT1DHPhn
Mild concern noticed this after quickly entering fullscreen on a video and checking the logs

[Vixea]

@Drakulix friendly ping, sorry if you're busy

[Vixea]

Yep it's a scan out issue no problem with the disable scan out env var, nope just didn't reproduce it with the game however watching a video did it so nope nevermind

[Drakulix]

I am not sure what to tell you, the kernel logs look like this might be an amdgpu bug.

The drm_info log (and your tests with disabling scanout) should that direct scanout is in fact active. The log also confirms that VRR is active, but I am not sure, if that has any impact on the issue you are seeing.

I recommend to turn of scanout via the environment variable and possibly open a mesa/amdgpu issue.

[Vixea]

Update: kernel issue fixed, after updating to 6.13.1-arch(yes I know about the bug) it turns out the psr issue wasn't the issue. VRR is with it disabled I have no issues or at least decreased to the point of not being noticeable.

[Vixea]

So basically another VRR issue on the list of many VRR issues, now why it behaves that way your guess is as good as main you'll think it'll be a constant stutter at minimum fresh rate not a complete halting of rendering.

[Drakulix]

So basically another VRR issue on the list of many VRR issues, now why it behaves that way your guess is as good as main you'll think it'll be a constant stutter at minimum fresh rate not a complete halting of rendering.

Okay so, just to confirm this: This issue only happens with VRR enabled and overlay planes in use, correct? Disabling either fixes it?

[onlyreportingissues]

So basically another VRR issue on the list of many VRR issues, now why it behaves that way your guess is as good as main you'll think it'll be a constant stutter at minimum fresh rate not a complete halting of rendering.

Okay so, just to confirm this: This issue only happens with VRR enabled and overlay planes in use, correct? Disabling either fixes it?

Fullscreen videos seem also a little laggy. Watched a movie recently and fullscreen windowed was less laggy than watching it in fullscreen.

(Using adaptive VRR)

---

OS: Fedora Linux 41 (Workstation Edition) x86_64
Kernel: Linux 6.14.0-0.0.next.20250207.318.vanilla.fc41.x86_64
Display (PL2745Q): 2560x1440 @ 100 Hz in 27" [External]
CPU: AMD Ryzen 5 5600 (12) @ 4.69 GHz
GPU: AMD Radeon RX 6600 [Discrete]

cosmic-comp 63995c4
(Fedora Copr - user ryanabx)

firefox-135.0-1.fc41.x86_64

[Vixea]

So basically another VRR issue on the list of many VRR issues, now why it behaves that way your guess is as good as main you'll think it'll be a constant stutter at minimum fresh rate not a complete halting of rendering.

Okay so, just to confirm this: This issue only happens with VRR enabled and overlay planes in use, correct? Disabling either fixes it?

How would I disable overlay planes? Do you mean the cursor?
And yes it only seems to happen with VRR, I would need to check the possible overlay issue later(once that question is answered)

[Vixea]

Or does entering fullscreen enable/use the overlay plane?
If that's the case then yes only happens with overlay and VRR enabled

[Drakulix]

How would I disable overlay planes?

COSMIC_DISABLE_OVERLAY_SCANOUT=1

Or does entering fullscreen enable/use the overlay plane?

No, on adaptive VRR this turns on VRR and it makes it way more likely that cosmic-comp is using direct scanout on the primary plane. (Which can also be disabled with COSMIC_DISABLE_DIRECT_SCANOUT=1, which will also disable overlay plane scanout and basically force composition for anything but cursors.)

[Vixea]

Tried disabled scan out, no issue both auto and always
Tried only overlay I noticed issues both with auto and always